1. Field of Invention
The present invention relates to a package structure of a light emitting diode. More particularly, the present invention relates to a package structure of a light emitting diode having a package housing of a silicon optical bench.
2. Description of Related Art
The mechanism of light emitting diodes (LEDs) relates to light emission resulting from the released energy during the recombination of electrons and holes in the semiconductor materials. Due to numerous advantages of the light emitting diodes including miniature sizes, durability, low-driven voltages, low electricity consumption, fast response speed and good monochromatism, they are widely applied as light emitting elements in various electronic products, display panels and communication products.
For the light emitting diodes of various types, the light emitting diodes can be categorized as visible light LEDs and non-visible light (infrared light) LEDs based on the emitting light wavelength. The visible light LEDs includes red, red-orange, orange, yellow, yellow-green, green, blue and white light LEDs. Following the energy preservation and environmental protection concepts promoted by the developed countries America, Europe and Japan, the whilte light LEDs become one of the most potential products among these LEDs. Because the white light LEDs have small sizes, low power consumption and long lifetime but without heat radiation, they can replace traditional white light bulbs by overcome typical problems of the white light bulb and become the green luminance source in the twenty-first century.
FIG. 1 shows a package structure for a conventional surface mounting device (SMD) type LED. Referring to FIG. 1, a package housing 10 having a trench 11 is provided and an LED chip 12 is placed onto a bottom of the trench 11. Two electrodes of the LED chip 12 are respectively connected to the exposed two leads 16, 18 set within the trench 11. For both leads 16, 18, one end is exposed within the trench, while the other end extends to the bottom surface of the housing 10. A transparent molding compound 19 is formed by filling transparent resin into the trench 11, and the LED chip 12 and the leads 16, 18 within the trench 11 are encapsulated by the transparent molding compound 19. During the LED operation, by applying voltages of different polarity respectively to the uncovered ends of two leads 16, 18 that extend to the bottom surface of the package structure, light is generated by the LED chip 12 and emits through the transparent molding compound 19.
For the conventional LED package structure, the housing 10 and the molding compound 19 are made of resin materials, such as, epoxy. However, the resin materials when exposure to UV light can easily become degenerated or fragile. Therefore, if UV LEDs or other LEDs of near UV wavelength are fitted in this conventional LED package structure, the emitting UV or near UV light may damage the packaging materials, thus lowering the brightness or accelerating aging of the device. As a result, the application of certain types of LEDs is severely limited by using this type of package structure.